Timepiece



March 11, 1969 J. R. SLAUGH 3,431,721

TIMEPIECE Filed June 20, 196? FIG I .INVENTOR James 1?. 5.40am! ATTORNEY United States Patent 3,431,721 TIMEPIECE James R. Slaugh, Manheim, Pa., assignor to Hamilton Watch Company, Lancaster, Pa., a corporation of Pennsylvania Continuation-impart of application Ser. No. 609,607, Jan. 16, 1967. This application June 20, 1967, Ser. No. 647,434 U.S. Cl. 58-127 9 Claims Int. Cl. G04b 19/12 ABSTRACT OF THE DISCLOSURE This invention relates to timepieces and more particularly to timepieces such as watches having dials which are readable under all light conditions.

This application is a continuation-in-part of applicants copending application, Ser. No. 609,607, filed Jan. 16, 1967, now abandoned.

Background of the invention It is common knowledge and an old practice to provide watch or clock dials iformed either with luminous numerals against a non-luminous background or a luminous background and non-luminous numerals to provide for readability under low light conditions. Examples of such timepieces are found in Junghans US. Patent No. 911,- 401, showing a clock or gauge dial having a luminous material as a background for the numerals, and Cuntz US. Patent No. 1,414,628, showing numerals having an outline formed of a luminous material. This type of dial normally uses a luminous substance of the tritium or radium activated type which exhibits readability in total darkness. It has also previously been known to provide clocks utilizing fluorescent materials which can be irradiated by ultra violet rays for reading in the dark. Such a clock is shown in Doyle U .S. Patent No. 2,680,813.

While timepieces utilizing luminous materials provide good readability in near or total darkness, it has been found that they are less than satisfactory and are difficult to read in semi-darkness. The timepieces are thus readily readable either in daylight or in total darkness but are more or less diflicult to read in lighting conditions between these two extremes, with the degree of dificulty in reading being dependent upon the amount of light available. Since darkness is seldom total and since the semi-darkness condition is more likely to be encountered than near total darkness, this difliculty is of a significant nature not only for casually used timepieces, but also for those used under more stringent conditions, such as by commercial or military vessels or vehicles or by commercial or military personnel, including divers.

Summary of the invention According to the present invention, it has now been found that it is possible to provide a timepiece, and most particularly a watch, which is readily readable, not only in ordinary daylight and in total or near total darkness, but also in all degrees of lighting therebetween. This result is achieved through the use of watch or clock dials having numerals or markers either formed of or outlined by a tritium or radium activated material which is readable in near or total darkness. These numerals or markers are of a color in contrast to the background color so that they are readily readable in ordinary daylight or interior lighting conditions. However, in addition to the foregoing, there is provided as a background coating for the dial a fluorescent or phosphorescent material which not only causes the outline of the numerals or markers to become illuminated, thereby making the dial readable in semi- 3,431,721 Patented Mar. 11, 1969 ice Objects of the invention It is accordingly a primary object of the present invention to provide an improved timepiece or watch having a dial readable under substantially all lighting conditions.

It is another object of the invention to provide a timepiece or watch having a dial readable under lighting conditions varying from bright sunlight to total darkness, including all lighting conditions between these two eX- tremes.

It is another object of the invention to provide an improved timepiece or watch dial utilizing numerals or markers which are luminous and which are mounted in a background which is fluorescent or phosphorescent.

It is still another object of the invention to provide an improved timepiece or watch dial having numerals or markers formed or outlined by a tritium or radium activated material mounted on a fluorescent or phosphorescent background wherein such numerals or markers are of a color contrasting to such background or outline under ordinary lighting conditions.

Brief description of the drawing These and further objects and advantages of the invention will become more apparent upon reference to the following specification, claims, and drawings, wherein:

FIGURE 1 is a plan view of a dial constructed according to one embodiment of the invention; and

FIGURE 2 is a plan view of a dial constructed according to another embodiment of the invention.

Description of the preferred embodiments Referring to FIGURE 1, there is seen a watch dial, indicated generally at 10, which carries a series of numerals 12-18 and markers collectively indicated at 20. According to the invention, the numerals 12-18 and markers 20 are formed of a conventional tritium or radium activated material which is readable in near or total darkness. In such materials radium or tritium gas is incorporated an organic molecule mixed with zinc sulfide phosphor and an appropriate adhesive for the radioactive material. A suitable colorant may be used to contrast with the background under ordinary room or daylight lighting conditions.

The numerals 12-18 and markers 20 are set oif against a background 22 which is coated with a known fluorescent or phosphorescent material, such as a sulfonamide resin containing fluorescent dye and an acrylic adhesive. The phosphorescent material may consist of zinc sulfide phosphor mixed with an appropriate adhesive. The dye is so chosen that the color of the background and of the numerals and markers are contrasting under ordinary lighting conditions.

The hands 24 and 26 are preferably coated with a luminous material, such as the tritium or radium activated materials utilized for the numerals and markers.

With a timepiece or watch of the foregoing type, visibility is provided under ordinary lighting conditions by the contrast in color between the numerals and markers and the background. A similar contrast is preferably secured between the hands 24 and 26- and background 22. Under semi darkness or dimly lit conditions, the watch is still readable, in contrast to prior devices, by virtue of the fluorescent or phosphorescent background 22 which causes the numerals and markers and hands to stand out in a thoroughly readable fashion under ordinary illumination of wavelengths of approximately 3 x10 meters or 40()0--7000 A., and also under the unexpected cooperative effect of the tritium or radium activated material.

A watch of this type possesses unusual readability in dimly lit areas or circumstances, such as theaters, night driving, or underwater activities. Needless to say, such a watch or clock provides a heretofore unavailable readability under all lighting circumstances, which is particularly useful for commercial, scientific or military purposes.

Referring to FIGURE 2, there is seen another embodiment of the invention wherein a timepiece dial 28 is provided with numerals 3036 and markers collectively indicated at 38 and hands 40 and 42. According to this embodiment of the invention, the numerals 3036 and markers 38 are formed with an outline indicated by the heavy lines which is formed of a luminous material such as tritium or radium activated materials described hereinabove. In a similar manner, the hands are provided with outlines of the same material. The background 44 constitutes a coating of fluorescent or phosphorescent material as described hereinabove. The portions of the numerals, markers and hands within the outlines may be simply uncoated or painted or may be formed of the same fluorescent or phosphorescent material constituting the background 44. This arrangement also provides for full timepiece readability in all lighting conditions ranging from full sunlight to total darkness.

While the foregoing embodiments of the invention have been discussed in terms of a background constituting the entire face of the timepiece or watch dial, it will be apparent that it would be possible to utilize fiourescent or phosphorescent materials over only a portion of the dial so long as adequate background is provided to enable one to distinguish the numerals and markers and hands under all lighting conditions. Various combinations and permutations will also be apparent.

Timepieces constructed according to the present invention possess the unique characteristics of being readable not only under daylight and total or near total darkness conditions, but also at substantially all varying degrees of lighting therebetween.

What is claimed and desired to be secured by United States Letters Patent is:

1. A timepiece having a dial including indicia means and indicia background means, one of said means being formed of a radioactive luminous material and the other of said means being formed of a material which emits 4 visible light when excited by radiation of the wavelength of 4000-7000 A.

2. A timepiece as set out in claim 1 wherein said indicia means are formed of said luminous material and said background means is formed of said material which radiates light when excited by said radiation.

3. A device as set out in claim 2 including timepiece hands at least partially coated with a luminous material.

4. A device as set out in claim 2 wherein said background is fluorescent.

5. A device as set out in claim 2 wherein said background is phosphorescent.

6. A device as set out in claim 3 wherein said luminous material is selected from the group consisting of tritium and radium activated materials.

7. A device as set out in claim 3 wherein said luminous material comprises tritium activated material.

8. A device as set out in claim 3- wherein said luminous material is selected from the group consisting of tritium and radium activated zinc sulfide phosphor and said background means is formed of a material selected from the group consisting of a sulfonamide resin containing fluorescent dye and an acrylic adhesive and a zinc sulfide phosphor mixed with an adhesive.

9. A device as set out in claim 3 wherein said indicia means comprises at least in part numerals.

References Cited UNITED STATES PATENTS 863,287 8/ 1907 Kunz 250-72 911,401 2/1909 Junghans 58-127 1,173,110 2/1916 Junghans 24()2.25 X 1,342,767 6/1920 Schlesinger 58-50 1,388,855 8/1921 Fordyce 58-50 1,413,971 4/ 1922 Cuntz 5850 2,023,934 12/1935 Moise 58-50 2,403,316 7/ 1946 Wallhausen 25 0-72 2,680,813 6/1954 Doyle 250-72 2,885,561 5/1959 Lange.

RICHARD B. WILKINSON, Primary Examiner.

S. A. WAL, Assistant Examiner.

U.S Cl. X.R. 58-50 

